TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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Bro has a 91 TPI that he recently purchased. It was having trouble staying running and he wound up replacing just about every sensor and plugs/wires/cap/coil, and added a set of LT1 injectors, EGR and has searched for vacuum leaks with no luck. We solved the staying running part (the stock injectors were shot) but now it wants to idle rough/miss badly.
updated***
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Last edited by 88ROC1LE; 09-12-2009 at 02:46 PM.
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Ok well lets start there and work our way from there. A code 43 indicates a problem with you ESC system. What it should do Is tell the ECM to retard the timing in the presents of a knock. What this code is saying is that you ECM has detected that your ESC module has told the ECM that it is constantly knocking regardless of how far the ECM pulls back the timing. What we need to do is first confirm what signal the ESC module sending to the ECM? Is it sending the 8 or 10V everything ok no knock present signal or 0V telling the ECM to retard the timing? If its 0V we have a problem with either the ESC module, the knock sensor or the associated wiring. If its 8 or 10V we need to confirm that the signal wire is not broken and has a good connection to the ECM. Most likely we will find some sort of problem but if not we need to determine whats causing it to knock. One step at a time though.
Just on a whim he went and changed out the ecm this morning, still no luck, getting codes 42 and 43 now on both ecm's, same running conditions on both ecm's. He told me the tach is jumping around like crazy now and that while he is holding the car at 3000rpm, the snap-on scan tool and tach are showing 6000+rpm and higher.
Oh well thats probably because your ignition control module is bad. It drives the tach and all that. Also as far as the ESC i forgot the 90-91s had the integrated ESC module. Unfortunetly i dont have a schematic for those to see how there set up so i cant say much. Ide suspect a broken wire, bad connection, or bad knock sensor. Start with the ignition control module though as the RPM has alot to do with the ECM control of spark and fuel. If the ECM dosnt know what RPM it is it will never work right.
Got the code 42 gone, had a broken wire. Code 43 and the crappy idle are still there, looking over the knock sensor and associated wiring again, brand new knock sensor and different ecm combo didn't work.
Update:
He threw in a new prom, ecm, knock sensor to ecm wiring, and a new distributor, the car still idles like crap. Not idling real high, just missing alot as we get in the throttle more. Still throwing code 43. If we disconnect to set timing the car still misses alot.
Running out of things for him to try.
